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Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
000
FGUS73 KBIS 091641
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-111500-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
1041 AM CST Thu Mar 9 2023
...SPRING FLOOD AND WATER RESOURCES OUTLOOK...
This Flood and Water Resources Outlook is for the James and Missouri
river basins of North Dakota, covering the period of 11 March
through 9 June, 2023. This outlook is the third and final rendition
of the Spring Flood Outlook. Going forward, the National Weather
Service will go back to the routine monthly issuance of the flood
probabilities on, or near, the fourth Thursday of every month.
The following message has four sections. The first provides some
text on the highlights of this outlook and conditions affecting the
local hydrology. The second section gives the current and
normal/historical risks of flooding as determined by the Ensemble
Streamflow Forecast model of the National Weather Service. The third
section gives the current probabilities for reaching flood stage at
the listed forecast locations. And finally, the fourth section
covers the risk of the river sites falling below the listed stages.
...Flood Outlook Highlights...
A persistent storm path has continued to add snow to the landscape,
especially along and south of the I-94 corridor. The additional
moisture in the form of Snow-Water Equivalent (SWE) has been
preserved by the cooler than normal temperatures and has slightly
increased the risk of flooding along a number of forecast locations.
Moisture added over the past two weeks has only slightly increased
the overall flood risk. Flood risk is now considered near normal to
slightly above normal along the Knife River and Spring Creek
watershed, as well as the Cannonball River. The Little Missouri and
Heart rivers remain somewhat below normal for flood risk. Missouri
River tributaries east of the Missouri River such as Apple Creek are
now near normal for flood risk. The exception being Beaver Creek
near Linton where flood risk remains below normal. Farther east, the
James River and Pipestem Creek above Jamestown remain slightly below
to near normal risk of flooding. However, the risk rises below I-94
to slightly above normal at LaMoure on the James River. Dry and warm
soils are still expected to substantially reduce runoff from melting
snow under all but the most extreme of melt conditions, including a
rain on snow scenario. However, the region has experienced well
below normal temperatures for quite some time now, and the closer we
get to April, the greater the chance of seeing a rapid change in
temperatures with daily highs potentially well above freezing. One
commonality across the majority of these watersheds is the effect
the warmer and drier than normal soils are having on flood risk. The
models continue to suggest that under anything resembling a normal
melt pattern, much of the existing SWE is expected to end up in the
ground.
All that being said, one should remember that while the region is
now nearing the end of the snow accumulation season, historically
speaking, overall precipitation trends upward as we go through March
and into April. This also highlights the increasing risk as each day
passes with little to no melt of the existing snowpack.
These flood risks will be updated on March 23rd, 2023 as a part of
the routine release of the probabilistic Flood and Water
Resources Outlook.
...Missouri and Yellowstone Rivers...
Snowpack and SWE values remain near normal across the majority of
the Missouri and Yellowstone basins in Montana. However, due to last
year`s drought, runoff from the upper basins is expected to be
somewhat below normal due to the dry soils. Accordingly, flood risks
along the Missouri and Yellowstone Rivers above Lake Sakakawea
should be considered near normal. This would include the risk of
high water due to ice jams. In the event of abnormally high spring
runoff above Garrison Dam, Lake Sakakawea is well below normal for
this time of year and has above normal storage available for any
excess runoff. Below Garrison Dam, runoff is not expected to be
enough to create flood problems due to high flow from the
tributaries. However, there is always a slight chance of high water
in the event of a rapid melt resulting in an ice jam if the
tributaries were to discharge their ice ahead of the Missouri River
opening up through the Bismarck/Mandan area. The risk of this would
appear to be near normal, but with each passing day, the risk of
this increases until such time as the Missouri River is open within
the Bismarck/Mandan area.
...Snowpack Conditions...
The snowpack has two distinct layers or components to it right now.
There is the snow/ice that was received early in the winter that
underwent some melting and consolidation during a warm period of
February. This part of the snowpack now more closely resembles
porous ice and is more resistant to melting than freshly received
snow. The remaining part of the snowpack is snow received largely
over the past two or three weeks. This relatively new and less
consolidated snow is easier to melt.
Snowpack across the Missouri and James River basins remains thinnest
in the western one-third of the state, and increases as one looks
farther east. SWE content between one and slightly over two inches
is common, with locally higher amounts west of a line from southern
McKenzie County over to western Grant county. A good fraction of
this region`s snowpack continues to occupy the deeper draws and
coulees. This shelters the snow from direct sunlight and inhibits
the overall melt rate. East of that line, widespread two and up to
five inches of SWE is possible all through the Prairie Pothole
Region of the state. Within the James River Basin, the Pipestem
Creek watershed has some of the lower SWE content, while the eastern
side of the James River Basin tends to be higher with four or more
inches of SWE being common with localized areas now having over six
inches of SWE.
...Current Drought Conditions...
The recent pattern of weekly storm events continues to increase the
snowpack south of Highway 200 across most of the state. In response
to some of the higher amounts of snow received in areas south of
I-94, and east of the Missouri River, have resulted in one-category
improvements for a number of counties. Plenty of SWE exists to erase
the moisture deficit if judiciously split between runoff and
recharge to soil moisture. At this point cautious optimism is
warranted that improvements will continue going forward.
...Reservoirs and Natural Wetlands...
With only a few exceptions all man-made reservoirs, livestock dams,
and natural wetlands are below their normal water levels for this
time of year.
...Soil Conditions...
Soils across the basin are quite dry. Along with the soils being
dry, the insulating effect of the early snow has kept the soils
under the snow warmer than one would expect based on the overall
colder than normal December and slightly warmer than normal January.
These warm and dry soils will allow infiltration of rainfall and
meltwater from the spring snowmelt season under all but the most
extreme of melt conditions.
...Weather Outlook...
In the 6-10 and 8-14 day outlooks, a cooler than normal weather
pattern is expected to continue while the above normal moisture is
favored to transition towards a more normal precipitation pattern.
Looking out to the weeks 3-4 outlook, the cooler than normal pattern
is favored to continue while precipitation is split between equal
chances for below normal, near normal, and above normal for the
western half of North Dakota, while the eastern half is slightly
favored for below normal precipitation. The three-month outlook for
March, April, and May favors a retention of the cooler than normal
pattern, while all of North Dakota falls under the equal chances for
below normal, near normal, or above normal precipitation.
One key thing to remember as the region goes through March is that
the historical normal for daily high temperatures in the Bismarck
area is 30.3 degrees Fahrenheit on March 1st, but steadily rises to
an average of 49.3 degrees on March 31st. So even if the region were
to remain cooler than normal through March, below normal
temperatures now include weather patterns that could create a gentle
melt pattern.
...Ice Conditions...
All small lakes and wetlands are covered with ice of variable
thickness. Lakes with substantial snow cover are likely to have
thinner ice due to the insulating effect of the deeper snow.
In Table 1 below, the current (CS) and historical (HS) or normal
probabilities of exceeding minor...moderate...and major flood stage
are listed for the valid time period.
CS values indicate the probability of reaching a flood category
based on current conditions.
HS values indicate the probability of reaching a flood category
based on historical or normal conditions.
When the value of CS is greater than HS...the probability of
exceeding that level is higher than normal. When the value of CS is
less than HS...the probability of exceeding that level is lower
than normal.
...Table 1--Probabilities for minor...moderate and major flooding...
Valid Period: 03/11/2023 - 06/09/2023
: Current and Historical
: Chances of Exceeding
: Flood Categories
: as a Percentage (%)
Categorical :
Flood Stages (FT) : Minor Moderate Major
Location Minor Mod Major : CS HS CS HS CS HS
-------- ----- ----- ----- : --- --- --- --- --- ---
:Pipestem
Pingree 11.0 13.0 15.0 : 5 12 <5 <5 <5 <5
:James River
Grace City 12.0 14.0 15.0 : <5 15 <5 9 <5 8
LaMoure 14.0 16.0 18.0 : 22 17 15 8 <5 <5
:Missouri River
Williston 22.0 24.0 26.0 : 7 42 <5 20 <5 8
:Cannonball River
Regent 22.0 24.0 26.0 : <5 <5 <5 <5 <5 <5
:Cedar Creek
Raleigh 12.0 14.0 16.0 : <5 9 <5 5 <5 <5
:Cannonball River
Breien 10.0 20.0 23.0 : 58 49 <5 <5 <5 <5
:Beaver Creek
Linton 12.0 14.0 16.0 : 9 45 <5 31 <5 13
:Little Muddy River
Williston 10.0 12.0 14.0 : 39 86 17 54 <5 14
:Little Missouri River
Marmarth 18.0 23.0 30.0 : <5 6 <5 <5 <5 <5
Medora 15.0 18.0 20.0 : 5 25 <5 8 <5 6
Watford City 20.0 24.0 30.0 : <5 <5 <5 <5 <5 <5
:Knife River
Manning 15.0 17.0 20.0 : 32 33 <5 6 <5 <5
:Spring Creek
Zap 14.0 18.0 20.0 : 30 31 22 17 17 15
:Knife River
Hazen 21.0 24.0 25.0 : 37 43 30 31 18 26
:Heart River
Mandan 17.0 23.0 28.0 : 14 26 <5 6 <5 <5
:Apple Creek
Menoken 15.0 16.0 17.0 : 68 68 52 60 16 38
Legend
CS = Conditional Simulation (Current Outlook)
HS = Historical Simulation
FT = Feet
In Table 2 below...the 95 through 5 percent columns indicate the
probability of exceeding the listed stage levels (FT) for the valid
time period.
...Table 2--Exceedance Probabilities...
Chance of Exceeding Stages
at Specific Locations
Valid Period: 03/11/2023 - 06/09/2023
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 6.1 6.3 6.6 7.8 9.2 10.5 11.0
:James River
Grace City 5.8 6.0 6.6 7.4 8.9 10.1 11.5
LaMoure 9.3 9.4 9.7 10.3 13.4 16.5 16.7
:Missouri River
Williston 16.8 17.3 17.8 18.4 19.3 20.9 22.8
:Cannonball River
Regent 7.7 7.8 8.2 8.9 9.9 10.6 13.5
:Cedar Creek
Raleigh 5.3 5.7 6.2 6.8 7.3 7.7 8.2
:Cannonball River
Breien 8.5 9.2 9.7 10.2 11.2 11.7 12.7
:Beaver Creek
Linton 6.1 6.4 6.8 8.3 10.2 11.8 13.1
:Little Muddy River
Williston 6.1 6.7 7.7 9.3 10.6 12.3 13.4
:Little Missouri River
Marmarth 2.0 2.2 2.7 4.1 8.6 11.6 14.5
Medora 2.3 2.6 3.6 4.8 9.6 12.4 15.5
Watford City -0.4 -0.1 1.7 3.3 6.2 7.8 11.1
:Knife River
Manning 7.8 8.1 8.4 11.5 15.7 16.2 16.7
:Spring Creek
Zap 6.6 7.1 8.0 9.8 17.3 25.3 27.9
:Knife River
Hazen 7.9 10.1 10.9 15.0 24.6 26.4 26.7
:Heart River
Mandan 3.4 3.9 5.1 6.9 12.7 18.7 22.4
:Apple Creek
Menoken 11.4 12.6 14.0 16.0 16.7 17.3 18.3
In Table 3 below...the 95 through 5 percent columns indicate the
probability of falling below the listed stage levels (FT) for
the valid time period.
...Table 3--Nonexceedance Probabilities...
Chance of Falling Below Stages
at Specific Locations
Valid Period: 03/11/2023 - 06/09/2023
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree 4.7 4.7 4.7 4.7 4.7 4.7 4.7
:James River
Grace City 4.0 4.0 4.0 4.0 4.0 4.0 4.0
LaMoure 6.8 6.8 6.8 6.8 6.8 6.8 6.6
:Missouri River
:Cannonball River
Regent 5.1 5.1 5.0 4.9 4.8 4.8 4.8
:Cedar Creek
Raleigh 0.9 0.9 0.9 0.9 0.8 0.6 0.6
:Cannonball River
Breien 2.0 2.0 2.0 2.0 2.0 2.0 1.9
:Beaver Creek
Linton 4.1 4.1 4.1 4.1 4.1 4.1 4.1
:Little Muddy River
Williston 4.6 4.6 4.6 4.6 4.5 4.5 4.4
:Little Missouri River
Marmarth 1.2 1.2 1.2 1.2 1.1 1.0 0.9
Medora 1.4 1.4 1.4 1.4 1.2 1.1 1.0
Watford City -1.4 -1.4 -1.4 -1.5 -1.8 -2.0 -2.0
:Knife River
Manning 6.0 6.0 6.0 5.9 5.6 5.5 5.5
:Spring Creek
Zap 4.4 4.4 4.4 4.4 4.4 4.3 4.3
:Knife River
Hazen 0.8 0.8 0.8 0.8 0.7 0.6 0.6
:Heart River
Mandan -0.7 -0.7 -0.7 -0.7 -1.1 -1.5 -1.5
:Apple Creek
Menoken 3.6 3.6 3.6 3.6 3.5 3.5 3.3
These long-range probabilistic outlooks contain forecast values that
are calculated using multiple season scenarios from 30 or more years
of climatological data...including current conditions of the
river...soil moisture...snow cover and 30 to 90 day long-range
outlooks of temperature and precipitation. By providing a range
of probabilities...the level of risk associated with long-range
planning decisions can be determined. These probabilistic
forecasts are part of the National Weather Service`s Advanced
Hydrologic Prediction Service.
Visit our web site weather.gov/bis for more weather and water
information.
The next outlook will be issued on 23 March.
$$
Schlag
- National Weather Service
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- Page last modified: Sep 6th, 2022 18:00 UTC